Ultrasound transducer with reduced aperture delay line

ABSTRACT

A delay line for an ultrasound transducer including: upper and lower surfaces, wherein the upper surface is configured to engage with an ultrasonic transducer and the lower surface is configured to engage with an object to be tested and the upper and lower surfaces have an area that is smaller than an area of the ultrasonic transducer; and at least one attachment face configured to attach to the ultrasound transducer. A method of applying ultrasonic energy to an object, the method including: applying a delay line to an object, wherein the delay line has: upper and lower surfaces, wherein the upper surface is configured to engage with an ultrasonic transducer and the lower surface is configured to engage with an object to be tested and the upper and lower surfaces have an area that is smaller than an area of the ultrasonic transducer; and at least one attachment face configured to attach to the ultrasound transducer; generating ultrasonic pulses via a transducer attached to the delay line; determining measurements based on the ultrasonic pulses; and determining characteristics of the object based on the measurements.

RELATED APPLICATION

This application claims priority to U.S. provisional patent applicationNo. 62/002,359 filed May 23, 2014, which is incorporated herein byreference.

FIELD

The present disclosure relates generally to ultrasound transducers. Moreparticularly, the present disclosure relates to a reduced aperture delayline for an ultrasound transducer used in industrial and commercialapplications.

BACKGROUND

An ultrasound device generally includes a transducer probe, a processingunit, transducer pulse controls and input and output elements in orderto acquire, process and display the data received by the ultrasounddevice. The transducer probe is placed against an object to be probedand then produces sound waves and receives the echoes in order togenerate data related to the object being probed.

Ultrasonic testing is a form of non-destructive testing that is used ina variety of industries and on a variety of materials. As an example,ultrasonic testing can used to test the thickness or integrity of amaterial or object. In one particular case, ultrasonic testing can beused to test fiber reinforced plastics such as those used in tanks andpipes.

In some applications, such as, for example, storage or transmission ofchemicals, accurate ultrasonic testing of tanks and pipes can be veryimportant in order to allow the longest life of the tanks or pipes whilealso ensuring safety such that the tanks or pipes do not leak or break.

It is, therefore, desirable to provide an improved transducer forultrasonic testing.

SUMMARY

In one aspect there is provided, a delay line for an ultrasoundtransducer, the delay line comprising: upper and lower surfaces, whereinthe upper surface is configured to engage with an ultrasonic transducerand the lower surface is configured to engage with an object to betested and the upper and lower surfaces have an area that is smallerthan an area of the ultrasonic transducer; and at least one attachmentface configured to attach to the ultrasound transducer.

In a particular case, the delay line includes a top portion engagingwith the object to be tested and a bottom portion engaging with thetransducer and the top portion and bottom portion are a single piece.

In another particular case, delay line is for testing fibreglassreinforced plastics.

In still another particular case, the area of the delay lines is betweenapproximately 10% and 40% of the area of the ultrasonic transducer.

In yet another particular case, a radius of the top portion is between10 mm to 20 mm and a height of the top portion is between 5 mm and 12mm.

In still yet another particular case, a radius of the bottom portion isbetween 15 mm and 25 mm and a height of the bottom portion is between 2mm and 7 mm.

In a particular case, a diameter of the top portion is smaller than adiameter of the bottom piece.

In another particular case, a length of longitudinal edges of the topportion are between 30 and 33 mm.

In another particular case, the top portion and the bottom portion aremade of a vulcanized elastomer block.

In another aspect, there is provided an ultrasound system having: atransducer; a delay line having: upper and lower surfaces, wherein theupper surface is configured to engage with an ultrasonic transducer andthe lower surface is configured to engage with an object to be testedand the upper and lower surfaces have an area that is smaller than anarea of the ultrasonic transducer; and at least one attachment faceconfigured to attach to the ultrasound transducer; an attachment deviceconfigured to secure the delay line to the transducer via the at leastone attachment face.

In another aspect, there is provided, a method of applying ultrasonicenergy to an object, the method including: applying a delay line to anobject, wherein the delay line has: upper and lower surfaces, whereinthe upper surface is configured to engage with an ultrasonic transducerand the lower surface is configured to engage with an object to betested and the upper and lower surfaces have an area that is smallerthan an area of the ultrasonic transducer; and at least one attachmentface configured to attach to the ultrasound transducer; generatingultrasonic pulses via a transducer attached to the delay line;determining measurements based on the ultrasonic pulses; and determiningcharacteristics of the object based on the measurements.

In a particular case, the object is a fiber reinforced plastic object.

In another particular case, the object surface has a radius of curvatureless than 600 mm.

In still another particular case, the measurements based on theultrasonic pulses includes, performing energy and force balancecalculations based on the ultrasonic pulses.

In still yet another particular case, the ultrasonic pulse have a widthof between 0.1 microsecond and 3 microseconds.

In yet another particular case, the ultrasonic pulses have a width of 1microsecond.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present disclosure will now be described, by way ofexample only, with reference to the attached Figures.

FIG. 1 illustrates an embodiment of a transducer with a delay line;

FIG. 2 is a perspective view of an embodiment of a delay line;

FIG. 3 is a top view of the delay line according to an embodiment;

FIG. 4 is a longitudinal side view of the delay line according to anembodiment;

FIG. 5 is a latitudinal side view of the delay line according to anembodiment; and

FIG. 6 is a flow chart of a method of applying ultrasonic energy to anobject according to an embodiment.

DETAILED DESCRIPTION

Generally, the present disclosure provides for an ultrasonic transducerhaving a reduced aperture delay line, the combination of the transducerand reduced aperture delay line is sometimes referred to as a reducedaperture transducer.

Ultrasound transducers are typically used with a delay line that ispositioned between the transducer itself and the object to be probed ortested. The delay line is generally a piece of material, for examplerubber, plastic, epoxy, or the like, placed in front of the transducer.Delay lines are intended to provide improved resolution of flaws nearthe surface of an object and are intended to provide an improved rangeand more accurate thickness measurements of the object. Further, whenused to apply ultrasonic energy to polymeric materials, delay lines mayact as coupling devices to improve the quality of an ultrasonic signalthat enters the object being probed.

FIG. 1 illustrates a transducer 10 with a delay line 100 according to anembodiment herein. Ultrasonic vibrations or pulses originate from aplurality of points along a face of the transducer 10. The transducer 10and delay 100 line are often circular but may also take other shapessuch as rectangular, square, or the like. The delay line 100 may beprotected by or surrounded by a cover 14. The cover 14 may be providedto, for example, hold the delay in position on the face of thetransducer 10 or the like. The transducer 10 may be connected, forexample via a wire or cable 16 to an ultrasound system 18, which mayinclude a display, a memory component, a processor, and the like. Inother cases, the transducer 10 may be wirelessly connected to theultrasound system 18.

In ultrasonic testing, the transducer 10 with delay line 100 is placedon an object 12 and ultrasonic vibrations are applied to the surface theobject 12. One particular application is for testing fiber reinforcedplastic (FRP) objects such as tanks, pipes or the like. In these typesof applications, the transducer 10 may generate periodic square-waveultrasonic pulses, with a pulse width in the range of 1 microsecond orless. The pulses are then transmitted through the delay line 100.

In some cases, the delay line 100 may be made of a block of vulcanizedelastomer with generally plane faces where the delay line 100 contactswith the face of the transducer 10 and the FRP object 12. In aparticular example, the ultrasonic pulses may have a pulse width ofapproximately 1 microsecond (1 μs) corresponding to a frequency ofapproximately 0.5 MegaHertz (MHz); whereby the pulse width correspondsto frequency by the relationship:Pulse-Width(μs)=1/(2×Frequency(MHz))In other cases, the ultrasonic pulse may be in a range fromapproximately 0.1 to 3 microseconds.

In industrial testing, the diameter of the face of the transducer 10that generates the ultrasonic vibrations is typically in the range ofapproximately 12 to 32 millimeters (mm). The size of the face of thetransducer 10 is determined based on a combination of the frequencyrequired and the energy input required. In a particular example, thediameter of the face of the transducer 10 is 25 mm.

In conventional ultrasonic testing the delay line is typically a disk ofapproximately 25 mm in diameter by 16 mm thick. In some cases, thediameter of the disk may be between 15 mm and 35 mm and may be between10 mm and 20 mm thick. In conventional systems the disk fits over theentire face of the transducer.

FIG. 2 illustrates a perspective view of an embodiment of a reducedaperture delay line 100. In a particular case, the delay line 100 may beformed from a vulcanized elastomer block. In a specific example, therubber formulation has a Shore A Durometer hardness of 86 to 88. Inother cases, the delay line 100 may be composed of any material thatexhibits dimensional and ultrasonic stability for the usage conditionsrequired; for example, rubber, plastic, epoxy, or the like. The materialshould also have the hardness required to meet the dimensional andultrasonic stability requirements for the usage conditions. In furthercases, the delay line 100 may be a “digital material”; generally meaningthat the delay line 100 is composed of an elastomer or polymer made in a3D digital printer.

The delay line 100 may include a top portion 110 and a bottom portion120. The top portion 110 may be smaller in diameter than the bottomportion 120. In some cases the top and bottom portions may be formedfrom as a single piece. In other cases, the top portion 110 may beattached to the bottom portion 120 by for example, epoxy, glue or thelike.

The bottom portion 120 may be configured to assist with mechanicalattachment of the delay line 100 to a transducer 10. For example,attachment faces 170 a and 170 b of the bottom portion 120 may be usedas an attaching surface by an attachment device, for example the cover14. The attachment may allow securing of the bottom portion 120 to theface of the transducer 10 such that the ultrasonic energy may betransmitted through the bottom portion 120 to the top portion 110. In aparticular example, the attachment device may use any suitable mechanismfor attachment; for example, the cover 14 or a clamp that clamps theattachment faces 170 a and 170 b to the face of the transducer 10. Inother cases, other sections of the bottom portion 120 may be used toattach the delay line 100 to the transducer 10.

The top portion 110 may include rounded latitudinal edges 130 andstraight longitudinal edges 140 in order to generally match the diameterof the face of the transducer 10. Similarly, the bottom portion 120 mayalso include rounded latitudinal edges 150 and straight longitudinaledges 160 in order to provide sufficient or corresponding surfaces forthe attachment to the transducer 10 and attachment device.

Ultrasonic testing requires energy and force balance calculations to beperformed on the vibrations applied. In a particular example, when thevibrations are applied using a conventional 32 mm diameter, the size ofthe face of the delay line is generally the same as the size of the faceof the transducer. Although not conventionally well understood, when theradius of curvature of the object surface is less than approximately 600mm, a conventional delay line having the same diameter as the face ofthe 32 mm transducer will not be in contact with the object surface atsome points due to the curvature of the object, which may cause errorsto accumulate due to fugitive energy losses that cannot be quantified.In industrial testing, delay lines may be applied on objects withdifferent radii of curvature, and the amount of energy that is returnedfrom the face of the delay line may be compared with the radius ofcurvature. Conventionally, when the radius of curvature of the objectsurface is less than 600 mm, statistical significant results are notgenerally attainable. This means that reliable energy and force balancecalculations may not be completed.

The delay line 100 illustrated in FIG. 2 uses an elastomer block with areduced face area compared to conventional delay lines to reduce thefugitive energy losses. By reducing the face area, some of theultrasonic energy is filtered out, or “thrown away”, increasingknowledge of the energy that is available to act on the work piece, andthus reducing the fugitive energy losses.

FIG. 3 illustrates a top view of the delay line 100. In a particularexample where the diameter of the transducer 10 is 32 mm, the radius ofthe top portion 110 may be approximately 16 mm and the radius of thebottom portion 120 may be approximately 19 mm. As shown in FIGS. 2 to 5,side portions of the conventional circular delay line have been cut awayto provide the reduced aperture delay line 100. In considering thereduced aperture delay line, it remains possible to consider a radiusmeasurement when considering the size of a circle used to generate thereduced aperture delay line. In other cases, the radius of the topportion may be between 10 mm and 20 mm and the radius of the bottomportion may be between 15 mm and 25 mm. In still other cases, the radiusof the top portion and the bottom portion may be related to the diameterof the transducer in order to provide adequate sizing of the delay linebased on the diameter of the transducer. Generally speaking, the widthof the delay line can be chosen to provide an appropriate coverage in arange include 10%, 30% or 40% of the area of the ultrasonic transducer10. The width of the delay line may also depend on the size (diameter)of the object to be measured.

FIG. 4 is a longitudinal side view of a delay line 100 and FIG. 5 is alatitudinal side view of a delay line 100. In a particular example wherethe diameter of the transducer 10 is 32 mm, the longitudinal side of thetop portion may be approximately 30 to 33 mm. Further, the top portionmay have a height of approximately 10 mm and the bottom portion 120 ofapproximately 6.5 mm, making for a height of approximately 16.5 mm forthe delay line 100. In further cases, the top portion may have a heightin the range of approximately 5 mm to 12 mm. In still further cases, thebottom portion may have a height in the range of approximately 2 mm to 7mm.

FIG. 6 illustrates a method 200 of applying ultrasonic energy to anobject.

At 210, the delay line 100 is applied to an object. The delay line 100is attached to an ultrasonic transducer, wherein a face of theultrasonic transducer is configured to generate ultrasonic pulses orvibrations. In some cases, the object will be a fiber reinforced plasticobject or the like. It is intended that with the use of the delay line100, more accurate measurements may be obtained on objects with a radiusof curvature of the object surface being less than 600 mm. The delayline 100 is also intended to provide accurate measurements when used onobjects with a larger radius of curvature.

At 220, the ultrasonic transducer generates ultrasonic pulses. Thediameter of the face of the transducer that generates the ultrasonicvibrations is typically in the range of approximately 10 mm to 32 mm.The generated ultrasonic pulses may have a pulse width of 0.1 μm to 3μm. In a particular case, the ultrasonic pulses may have a pulse widthof 1 μm corresponding to a frequency of 0.5 MHz.

At 230, measurements are generated from the ultrasonic pulses beingapplied to the object. Reflections of the ultrasonic pulses fromfeatures and barriers within the object are received through the delayline 100 and the transducer 10. These reflections are translated intomeasurements that are represented by the time after a pulse is appliedand the magnitude of received vibrations.

At 240, calculations applied to the measurements may determinecharacteristics of the material being probed including flaw location andsize, signal attenuations, transit times, time-series variation of thereceived magnitudes, and the like.

In the preceding description, for purposes of explanation, numerousdetails are set forth in order to provide a thorough understanding ofthe embodiments. However, it will be apparent to one skilled in the artthat these specific details may not be required. In other instances,well-known structures are shown in block diagram form in order not toobscure the understanding.

The above-described embodiments are intended to be examples only.Alterations, modifications and variations can be effected to theparticular embodiments by those of skill in the art without departingfrom the scope, which is defined solely by the claims appended hereto.

The invention claimed is:
 1. A delay line for an ultrasonic transducerfor use in ultrasonic testing of a solid object having a curvature, thedelay line comprising: a top portion comprising an upper surface,wherein a radius of the top portion is between 10 mm and 20 mm and aheight of the top portion is between 5 mm and 12 mm; a bottom portioncomprising a lower surface, wherein a radius of the bottom portion isbetween 15 mm and 25 mm and a height of the bottom portion is between 2mm and 7 mm, wherein: the top portion and bottom portion are formed as asingle piece of vulcanized elastomer, the lower surface is configured toengage with the ultrasonic transducer and the upper surface isconfigured to engage with the solid object to be tested, the upper andlower surfaces each have a surface area that is smaller than a surfacearea of a face of the ultrasonic transducer, and the surface area ofeach of the upper and lower surfaces is determined based on thecurvature of the solid object to reduce fugitive energy losses.
 2. Adelay line according to claim 1, wherein the delay line is configuredfor testing fibreglass reinforced plastics.
 3. A delay line according toclaim 1, wherein a surface area of the upper surface of the delay lineis between approximately 10% and 40% of a surface area of the face ofthe ultrasonic transducer.
 4. A delay line according to claim 1, whereina length of longitudinal edges of the top portion are between 30 mm and33 mm.
 5. A delay line according to claim 1, wherein the top portion andthe bottom portion are made of a vulcanized elastomer block.
 6. Anultrasound system for use in ultrasonic testing of a solid object havinga curvature, the ultrasound system comprising: an ultrasonic transducer;a delay line according to claim 1; and an attachment device configuredto secure the delay line to the ultrasonic transducer.
 7. A delay lineaccording to claim 1, wherein the delay line further comprises at leastone attachment face configured to attach the delay line to theultrasonic transducer.
 8. A system according to claim 1, wherein thesolid object having a curvature has a radius of curvature less than 600mm.
 9. A delay line for an ultrasonic transducer for use in ultrasonictesting of a solid object having a curvature, the delay line comprising:a top portion comprising an upper surface, wherein a radius of the topportion is between 10 mm and 20 mm and a height of the top portion isbetween 5 mm and 12 mm; a bottom portion comprising a lower surface,wherein: the lower surface is configured to engage with the ultrasonictransducer and the upper surface is configured to engage with the solidobject to be tested, the upper and lower surfaces each have a surfacearea that is smaller than a surface area of a face of the ultrasonictransducer, and the surface area of the lower surface is determinedbased on the curvature of the solid object and the surface area of theupper surface to reduce fugitive energy losses.
 10. A delay lineaccording to claim 9, wherein a radius of the bottom portion is between15 mm and 25 mm and a height of the bottom portion is between 2 mm and 7mm.
 11. A delay line according to claim 9, wherein a length oflongitudinal edges of the top portion are between 30 mm and 33 mm.
 12. Adelay line according to claim 9, wherein the top portion and the bottomportion are made of a vulcanized elastomer block.